Modification of Drosophila cell surfaces by concanavalin A

The effect of Con A on the surface morphology of cultured cells of Drosophila melanogaster growing on coverglasses was examined by scanning electron microscopy. With low lectin concentrations (5--10 microgram/ml) surface filaments disappeared and the cells flattened and spread against the glass surface. Cytoplasmic fusion bridges were observed in areas where cells made contact. Concentrations of Con A ranging between 50--500 microgram/ml caused cell shrinkage and surface distortions without cell flattening and filament loss. These morphologic effects were not apparent if Con A binding sites were blocked by preincubation with alpha-methyl-D-mannopyranoside before application to the cell cultures. However, once the Con A-mediated changes were in effect, the cells failed to show recovery when they were returned to growth medium and a majority of the cells on the coverglasses degenerated. Presumably the cells whose morphology appears unaffected by Con A treatment are the survivors that repopulate cultures returned to growth medium.